Metal tube press



Sept. 22, 1959 M. ARENZ METAL. TUBE PRESS Filed Oct. 1, 1956 2 Sheets-Sheet l sebt; 22, 1959 Filed Oct. 1, 1956 M. ARENZ METAL TUBE PRESS 2 Sheets-Sheet 2 METAL TUBE PRESS Matthias Arenz, Dusseldorf-Lintorf, Germany, assignor to Schloemann Aktiengesellschaft, Dusseldorf, Germany Application October 1, 1956, Serial No. 613,076

Claims priority, application Germany October 3, 1955 Claims. (Cl. 207-3) In metal tube presses having a container for an ingot or billet to be extruded, a die situated in the end of the container, and a ram slidable in the container, it is known to pass a piercing mandrel through the ram, the shaft of which piercing mandrel is supported against an abutment situated on a mandrel crossbeam and is slidable in the direction of extrusion independently of the mandrel crossbeam. Compare for example German patent specification 822,988, issued November 29, 1951, and US. patent application Ser. No. 500,504, filed April 11, 1955. This known construction prevents rupture of the front end of the mandrel, which may occur when the extrusion material flowing through the die exerts by friction so great a traction on the mandrel that the mandrel, which is already weakened by the temperature, is no longer able to withstand this traction. Thus in the known construction the piercer mandrel performs a relative stroke in relation to the ram during the working of the press, the magnitude of which relative stroke is dependent upon the material to be extruded, upon the length of the ingot and upon the deformation degree of the material. The deformation degree is at the same time determined by the ratio of the cross-section of the container bore to the cross-section of the extruded tube. The magnitude of the resultant relative stroke varies greatly. In the known device, the length of the mandrel must now be so dimensioned that the mandrel is also sufliciently long even for those cases in which the nature of the material to be extruded, the length of the ingots used, and the deformation degree of the material require a very long relative stroke. In those cases in which only a small relative stroke occurs, use has therefore hitherto been made of a mandrel the length of which is greater than is really required.

Inter alia, the consumption of high-grade mandrel steel is a decisive factor in the economy of the production of metal tubes by means of extrusion. Any saving of mandrel steel results in an appreciable increase in the economy of the extrusion of metal tubes. The use of mandrels which are longer than is necessary, however, renders the extrusion work uneconomic. The object of the invention is to enable a short and hence relatively inexpensive piercing mandrel to be used in those cases in which only a small relative stroke of the piercing mandrel occurs, and a long piercing mandrel to be used in those cases in which the relative stroke is large. The invention achieves this by so arranging the abutment in the mandrel crossbeam to be displaceable in the direction of extrusion and to be adjustable by means of an adjusting device.

When the surface of the end of the piercing mandrel has become rough after relatively long use, the mandrel tends during extrusion to perform a longer relative stroke than when it is new and smooth. If, however, the length of the possible relative movement of the mandrel in relation to the mandrel crossbeam is limited so as to correspond to the conditions with a new piercing mandrel, the possibility of the mandrel moving forward before complete extrusion of the ingot used is limited, so that the risk of rupture of the mandrel recurs. In order to pre- Patented Sept. 22, 1959 vent this, according to a further development of the invention use is made of a control device which stops the working stroke of the ram and which is actuated before an end crossbeam located at the rear end of the mandrel shaft encounters a stop on the mandrel crossbeam.

Further objects and features of the invention will be clear from the description, the drawing and the claims.

The drawing illustrates one exemplified embodiment of the invention.

Figure 1 is a vertical longitudinal section through a vertical metal tube press according to the invention, and Figure 2 shows the upper parts of this press on a larger Scale.

1n the bottom part of a press column 1 is mounted a pressure block 2, against which is supported the die 3, which in turn partially close a container 4 in the downward direction. A ram 6 is capable of being driven into the bore 5 in the container 4. Axially slidable in said ram 6 is a piercing mandrel 7, which can enter the bore 3a of the die by its bottom end and then forms together with the die an annular gap from which can emerge the material to be extruded from the container 4 by the ram 6. This material to be extruded is inserted in the container bore 5, for example in the form of a heated aluminium ingot or billet 8. The ram 6 is rigidly connected through an intermediate piece 9 to a plunger 10, which is slidable in a press cylinder 11, when pressure fluid is admitted into the press cylinder in known manner. An inserted tube 12 is rigidly connected to the press plunger 10 and projects to the rear out of the press cylinder 11 and is rigidly connected there to a withdrawal crossbeam 13,

I to which are connected withdrawal plungers 14, which are slidable in withdrawal cylinders 15. When pressure fluid is admitted into the cylinders 15 the plungers 14 are thus pushed upward, carrying the ram 6 with them by way of the withdrawal crossbeam 13, the tube 12 and the plunger 10. The inserted tube 12 is held in the withdrawal crossbeam 13 by means of a nut 16, which simultaneously serves as a stop for a piercing mandrel crossbeam 17. The latter is connected to the piercing mandrel 7 by way of a piercing mandrel shaft 18, which is passed through the insert tube 12. The piercing mandrel shaft 18 has a shoulder 19, by means of which it can be supported against an abutment in the form of a bush 20 which is held in the piercing mandrel crossbeam 17 by means of a screwthread 21, the bush 20 being screwed into an insert bush 22, which sits firmly in the piercing mandrel crossbeam 17. Said bush 20 can be turned by a worm wheel 23, which possesses one or more longitudinal grooves 24, in which engages a lug or snout 25 of the bush 20. The worm wheel 23 can be turned by a worm 26, but is axially non-displaceable, so that on its rotation the bush 20 is turned with it, and, as it rotates, screws into the screwthread 21 or, on rotation in the opposite direction, unscrews from the screwthread 21. The worm 26 projects out of its housing by one end and carries there a handcrank and any desired turning device. The piercing mandrel shaft 18 has at its rear end 18a a screwthread on which is screwed a nut 27, which presses an end crossbeam 28 on to a shoulder 29 of the piercing mandrel shaft. The end crossbeam 28 carries a stop 30 which by means of nuts 31 can be fixed to be higher or lower in relation to the end crossbeam 28. The piercing mandrel crossbeam 17 carries piston rods 32, on which are located pistons (not illustrated) which can be moved upwardly or downwardly in the piercing mandrel cylinders 33 by means of hydraulic operation by water or oil. The piercing mandrel crossbeam 17 carries a switch, diagrammatically represented in Figure 2 by a switch casing 34, a movable switch member shown in its closed position at 35 and in its open position at 35a, and a switch-operating lever 36 pivoted at its upper end to the casing 34, and

carrying a roller 37 at its free end. In the closed position the switch member 35 connects two electric lines 38, the connection of said lines being broken when the switch member 34 is in the open position. As the end'crossbeam "28 descends relatively to the mandrel cross-beam 17, the cam-shaped lower end of the stop member 30 approaches the roller 37, and finally deflects this roller, and the lever 36, toward the right, this movement being transmitted to the switch-operating lever 36 by any convenient link, indicated by dotted lines. The lines 38 serve to control the admission of pressure fluid to the cylinder 11, the circuit being such, in manner not shown in 'thedrawing, that the admission of pressure fluid into the cylinder is interrupted when the switch member 35 passes from the closed position into the open position 35a. A further advance of the ram 6 is thus rendered impossible by "the switch member 35 opening.

The withdrawal crossbeam 13 is connected to the piercing mandrel crossbeam 17 through two tractive members, namely-the tractive rods 39. The latter are screwed by screwthreads into the withdrawal crossbeam 13 and 'by turning can be adjusted in the longitudinal direction in relation to the withdrawal crossbeam 13. They pass freely through the piercing mandrel crossbeam 17 and carry at their upper ends a fixed cap 40, which may, for example, be constructed as a nut. When the withdrawal crossbeam 13 is moved downward by the press plunger 10, the piercing mandrel crossbeam 17 must therefore follow by constraint. The piercing mandrel crossbeam 17 can, however, perform a downward movement independently of the ram 6 and of the withdrawal crossbeam 13 until it encounters the nut 16 which is mounted on the withdrawal crossbeam 13 and is constructed as a stop for the piercing mandrel crossbeam 17. By turning the tractive rods 39 and thereby screwing them out of or into the withdrawal crossbeam 13 to a greater or lesser extent, it is possible to fix the magnitude of the relative stroke which the piercing mandrel crossbeam 17 can perform in relation to the withdrawal crossbeam '13.

The end crossbeam 28 carries two plungers 50, 'disposed opposite one another at an angle to the plane of the drawing. Only one is shown, the other being in front of the plane of section. Each plunger plunges into a cylinder (only one of which is shown) which is mounted on the crossbeam 17. This cylinder has a narrow outlet and inlet and is filled with fluid. This arrangement acts as a dash-pot, and brakes or decelerates the movement of the end crossbeam.

To use the press, use is first made of a mandrel of which the length is so small that it is just sufliciently long to enable piercing to be carried out and to enable the relative stroke expected under the particular conditions in relation to the ram to be carried out. By adjustment of the tractive members 39, the stroke that can be performed by the piercing mandrel crossbeam 17 in relation to the withdrawal crossbeam 13 is dimensioned to be approximately equal to the height of the ingots 8 used. The mandrel 7 projects beyond the ram 6 by about millimetres at the most. In a known manner, by admitting pressure fluid into the press cylinder 11, an ingot 8 is pushed into the container 4, and then an upsetting stroke is exerted on it, the ram 6, taking the piercing mandrel 7 with it, upsetting the ingot 8 in the container bore 5 so that it lies tightly against the inner wall faces of the container bore. When, after the ingot has been upset, it is now pierced by the piercing mandrel 7 moving downward, the tip of the mandrel 7 advances downwardly to such extent that it penetrates into the opening of the die 3 and together with the latter forms the outlet gap for the extrusion now commencing. The downward movement of the piercing mandrel 7 is fixed by the adjustment-of the maximum distance between the two crossbeams 13 and 17. If extrusion is now commenced by moving the ram 6 downwardly, the extrusion material flowing out exerts by friction a traction on the mandrel in the region of the die. The mandrel is initially held fast by the amount of the ingot 8 located farther upwards and not yet flowing. As extrusion progresses further, the traction of the extrusion material flowing out and of the finished tube on the mandrel becomes so great, however, that the mandrel is driven. Its drive comes to an end by constraint when the end crossbeam 23 encounters the stop 41 of the piercing mandrel crossbeam 17 If extrusion of the ingot is not yet completed in this case, there is a risk that the extrusion material flowing out further will rupture the mandrel. The switch 34 serves as security against this danger and is operated by'the stop member 30 just before the end crossbeam 28 encounters the stop 41, this operation interrupting the further extrusion operation.

Thus inter alia the invention enables the length of the mandrel 7 to be used to be adapted to the length of the ingot 8 used and to the relative stroke the mandrel must perform in relation to thepiercing mandrel crossbeam 17 during extrusion in order to avoid rupture of the mandrel towards the end of the working-of the press. If the mandrel is still smooth and new, it is driven a relatively short distance by the extrusion material flowing out, so that extrusion is completed before the end crossbeam 28 encounters the stop 41. If, on the other hand, the bottom end of the mandrel has become rough through wear, the mandrel performs a more rapid relative movement in relation to the mandrel crossbeam 17, the consequence of this being that the end crossbeam "28 encounters the stop 41 before the extrusion process has ended. The consequent risk of rupture of the mandrel as a result is averted by the control device 30, 34. The operation of the control device 30, 34 is thus also an indication to the operator that the roughness of the surface of the mandrel has exceeded an economical value. He will then change the mandrel for another one.

What I claim is:

1. A metal tube extrusion .press, comprising: a container for a billet to be extruded, a die located at the end of the container, a hollow :press ram slidable in the container, a mandrel shaft, a piercing mandrel carried by the mandrel shaft and guided through the press ram, a mandrel cross-beam, means to move the cross beam in the direction of extrusion for moving the mandrel relative'to the die, the mandrel shaft being freely displaceable in the direction of extrusion independently of the mandrel cross-beam so that it is able to yield to forces acting upon the mandrel in the extrusion direction, a shoulder on the mandrel shaft, and a bush mounted on the cross-beam and longitudinally adjustable relatively thereto in the direction of extrusion, the forward end of this bush constituting an abutment adapted to engage the shoulder on movement of the cross-beam to move the mandrel therewith, so that by adjusting the bush the point of engagement of the mandrel shaft is adjusted in an axial direction relatively to the mandrel cross-beam so as to enable piercing mandrels of diiferent lengths to be employed.

2. A metal tube extrusion press as claimed in claim 1, further comprising: an end cross-beam secured to the rear end of the mandrel shaft, and a stop mounted on the end crossbeam adapted to engage the mandrel cross-beam upon longitudinal displaceability of the mandrel in 'relation to the mandrel cross-beam to limit such displacement.

3. A metal tube extrusion press as claimed in claim 2, comprising controlling means actuated by the displacement of the mandrel relative to the mandrel cross-beam for stopping the press ram before the stop engages the mandrel cross-beam.

4. A metal tube extrusion press as claimed in claim 3, the said controlling means including: a circuit controlling the press ram, an-electric switch mounted on the mandrel cross-beam adapted to open and close said circuit, and a lever operatively connected with the switch, said lever being positioned in the path of said stop and adapted to be actuated thereby.

5. A metal tube extrusion press as claimed in claim 1, further including power means for adjusting said bush.

References Cited in the file of this patent 6 Schlenstedt Aug. 17, 1915 Oehmig et a1 Apr. 3, 1928 Albers Sept. 1, 1936 Sparks Jan. 3, 1939 Schenk Oct. 23, 1945 FOREIGN PATENTS Italy Dec. 29, 1954 

